One interesting detail I came across while researching teratogens is that a protein-deficient diet may enhance the effects of xenobiotics in general.
For example, dietary protein deficiency along with exposure to inorganic arsenic through injection in mice was found to increase risk of birth defects, possibly because of lack of methyl donors for arsenic methylation (1). Also, high-dose caffeine teratogenicity is increased when in combination with protein deficiency (2).
Other xenobiotics such as tobacco carcinogens, anticonvulsants and sedatives appear to be teratogenic depending on the status of the cytochrome P450 system of the fetus (1). The effect may or may not be related to protein deficiency. The toxicity is thought to occur due to lack of anitoxidative enzymes such as GSH peroxidase and GSH reductase, which would increased endogenous oxidative stress and cumulative damage (3).
1. Lammon CA, Hood RD. Effects of protein deficient diets on the developmental toxicity of inorganic arsenic in mice. Birth Defects Res B Dev Reprod Toxicol 2004;71:124-34.
2. Nehlig A, Debry G. Potential teratogenic and neurodevelopmental consequences of coffee and caffeine exposure: a review on human and animal data. Neurotoxicol Teratol 1994;16:531-43.
3. Wells PG, Kim PM, Laposa RR, Nicol CJ, Parman T, Winn LM. Oxidative damage in chemical teratogenesis. Mutat Res 1997;396:65-78.